Some internal combustion engines include an adjustable or slideable camshaft assembly. The camshaft assembly includes a base camshaft that is rotatable about a cam axis, and a sliding camshaft that is slideably attached to the base camshaft for axial movement along the cam axis relative to the base camshaft. The sliding camshaft is rotatable with the base camshaft about the cam axis. The sliding camshaft is moveable between at least two different axial positions along the cam axis, relative to the base camshaft. Each different position of the sliding camshaft presents a different cam lobe having a different lobe profile for engaging a respective valve stem of the engine. Accordingly, by adjusting the position of the sliding camshaft along the cam axis relative to the base camshaft, the cam profile that each valve stem of the engine follows may be changed. It is known to form the sliding camshaft from a high carbon steel, such as AISI 52100 alloy steel.